Blind Carrier Frequency Offset Estimation Based on Eighth-Order Statistics for Coherent Optical QAM Systems

We propose a carrier frequency offset estimation (FOE) algorithm based on eighth-order statistics for optical quadrature amplitude modulation (QAM) signals. The FOE algorithm does not involve fast Fourier transformation and can be implemented by hardware with little memory and computation resources. Simulation results show that in a 10.709-GBaud/s optical 16-QAM system, carrier frequency offset ranging between ± 1.25 GHz can be estimated with a uniform standard deviation of 2 MHz when the optical signal-to-noise ratio is 17 dB and 410symbols are utilized.